Gas separation is useful in many industries and can typically be accomplished by flowing a mixture of gases over an adsorbent material that preferentially adsorbs one or more gas components, while not adsorbing one or more other gas components. The non-adsorbed components are recovered as a separate product.
One particular type of gas separation technology is swing adsorption, such as temperature swing adsorption (TSA), pressure swing adsorption (PSA), partial pressure purge swing adsorption (PPSA), rapid cycle pressure swing adsorption (RCPSA), rapid cycle partial pressure swing adsorption (RCPPSA), and not limited to but also combinations of the fore mentioned processes, such as pressure and temperature swing adsorption. As an example, PSA processes rely on the phenomenon of gases being more readily adsorbed within the pore structure or free volume of an adsorbent material when the gas is under pressure. That is, the higher the gas pressure, the greater the amount of readily-adsorbed gas adsorbed. When the pressure is reduced, the adsorbed component is released, or desorbed from the adsorbent material.
The swing adsorption processes (e.g., PSA and TSA) may be used to separate gases of a gas mixture because different gases tend to fill the micropore of the adsorbent material to different extents. For example, if a gas mixture, such as natural gas, is passed under pressure through a vessel containing an adsorbent material that is more selective towards carbon dioxide than it is for methane, at least a portion of the carbon dioxide is selectively adsorbed by the adsorbent material, and the gas exiting the vessel is enriched in methane. When the adsorbent material reaches the end of its capacity to adsorb carbon dioxide, it is regenerated in a PSA process, for example, by reducing the pressure, thereby releasing the adsorbed carbon dioxide. The adsorbent material is then typically purged and repressurized. Then, the adsorbent material is ready for another adsorption cycle.
The swing adsorption processes typically involve one or more adsorbent bed units, which include adsorbent beds disposed within a housing configured to maintain fluids at various pressures for different steps in an adsorption cycle within the unit. These adsorbent bed units utilize different packing material in the bed structures. For example, the adsorbent bed units utilize checker brick, pebble beds or other available packing. As an enhancement, some adsorbent bed units may utilize engineered packing within the bed structure. The engineered packing may include a material provided in a specific configuration, such as a honeycomb, ceramic forms or the like.
Further, various adsorbent bed units may be coupled together with conduits and valves to manage the flow of fluids. Orchestrating these adsorbent bed units involves coordinating the cycles for each adsorbent bed unit with other adsorbent bed units in the system. A complete PSA cycle can vary from seconds to minutes as it transfers a plurality of gaseous streams through one or more of the adsorbent bed units.
Typical sour gas treating facilities may use amine systems to remove acid gas from hydrocarbon feed stream. The process utilizes the amine system to divide the streams into a water saturated hydrocarbon stream and a water saturated acid gas stream. The hydrocarbon stream may then be monetized, which typically requires some level of dehydration. For cryogenic applications, the hydrocarbon stream may be passed through a molecular sieve system to form a dry sweet gas stream. The acid gas stream may be reinjected into the ground which also requires some level of dehydration. The acid gas stream from the amine system may be passed to a tri-ethylene glycol (TEG) system to form a dry acid gas stream. Unfortunately, typical amine systems require the gas streams to be saturated with water which results in the use of large amounts of water and requires additional make-up water for the moisture (e.g., water) lost in the hydrocarbon and acid gas streams. The requirement for water may be problematic in regions that do not have sufficient water supplies and/or in regions where disposal of water may be expensive. Further, the use of the large amounts of water may also result in larger equipment footprints.
Accordingly, there remains a need in the industry for apparatus, methods, and systems that provide enhancements to the processing of gaseous streams with adsorbent beds. The present techniques provide enhancements by utilizing swing adsorption processes to separate contaminants from a feed stream and regenerate the adsorbent bed units with less water than utilized in conventional approaches. The present techniques overcomes the drawbacks of conventional systems by using a specific configuration.